Frequently asked question

  • The main differences between API and NS-1

    The difference in thread structure (benchmark marking - all products);

    ·Differences in hardness test locations (NS-1 adds full section hardness inspection - all products);

    ·The requirements for cold rolling (NS-1 clearly requires threads and stress reducing grooves to undergo cold rolling treatment, and has requirements for rolling the rounded corners at the root of drill collar elevators and slips - all products);

    ·The difference in impact energy (NS-1 products require testing under low temperature -20 ℃ conditions);

    ·The difference in wall thickness difference (NS-1 specifies the requirements for full length wall thickness difference and two end wall thickness difference);

    ·Requirements for the type and position of product marking slots;

    ·Specific size requirements for wear-resistant tape welding types;

    ·Other recommended requirements.

  • Malfunctions and solutions of screw drilling tools

    Abnormal phenomenon 1: The pressure gauge suddenly increases.

    Possible reasons: Motor stalling or motor drive shaft jamming, drill bit water hole blocked

    Judgment and handling method: Motor stall: Raise the drilling tool by 0.3-0.6M, check the circulating pressure, gradually increase the drilling pressure, and the pressure gauge will gradually rise, all of which are normal. It can be confirmed that it is stall. The motor drive shaft is stuck, and the drill bit water hole is blocked. Lift the drill bit off the bottom of the well, and the pressure gauge reading is still very high. Only the drilling tool can be checked or the drill bit can be replaced.

    Abnormal phenomenon 2: The pressure on the pressure gauge decreases slowly

    Possible reasons: Changes in circulating pressure loss, damage to drill pipe

    Judgment and handling method: Check the drilling fluid flow rate, slightly lift the drilling tools, and if the pressure gauge reading is still lower than the circulating pressure, propose wellbore inspection

    Abnormal phenomenon 3: No footage taken

    Possible causes: geological changes, motor stall, bypass valve in "open" position, damaged universal joint shaft, damaged drill bit, damaged drill bit

    Judgment and handling method: Appropriately change the drilling pressure and circulating flow rate (note that it must be within the allowable direction), increase the reading on the pressure gauge, lift the drilling tool away from the bottom of the well, check the circulating pressure, start from a small drilling pressure, gradually increase the drilling pressure, lower the reading on the pressure gauge, slightly lift the drilling tool, start and stop the drilling pump twice but still ineffective. If it is necessary to lift the wellbore, replace and check the bypass valve, long and long with pressure fluctuations, slightly lift the drilling tool, and the pressure fluctuation range is smaller. Only the drilling tool can be removed, checked, replaced, and replaced with a new drill bit.

  • Classification and characteristics of shock absorber jamming tools

    According to its structure, the shock-absorbing tool is basically of two types: hydraulic and mechanical;

    Their common characteristics are:

    Capable of circulating drilling fluid, with a central channel for circulating drilling fluid;

    Capable of transmitting torque, with no circumferential movement between the spindle and outer cylinder;

    High strength sealing, the inner liquid cannot leak out, and the outer liquid cannot infiltrate;

    There is an energy storage mechanism that can store the elastic energy generated by the extension or compression of the drilling tool, and then suddenly release it to generate high-speed motion;

    There should be a shock-absorbing couple, that is, a pair of contradictory couples composed of an impact body and a impact bearing body;

    There should be a connecting mechanism, as it is connected to the middle of the drill string for work, so both the upper and lower parts should have threads connected to the drill string.

  • General repair criteria for drilling jars

    During normal drilling, if the working time of the drilling jar reaches the following specifications, it should be recycled and repaired.

    When the well temperature is above 190 ℃, work for 240 hours;

    When the well temperature is (150~190) ℃, work for 500 hours;

    1.3 When the well temperature is below 150 ℃, work for 720 hours;

    During normal drilling, although the drilling jar has not worked for the specified time, it should be retrieved and repaired if it has undergone intense shaking operations or if bending deformation or threads at both ends do not comply with relevant regulations are found during drilling.

  • General criteria for scrapping drilling jars

    If the outer diameter of the drilling jar is worn out and the outer diameter of the inner thread of the outer cylinder expands beyond the specifications in the table below, it should be scrapped.

    Specification (MM): 121 159 165 197 203

    Outer diameter wear (mm): 3.17,4.76,4.76,6.35,9.33

    Outer diameter expansion of inner thread of outer cylinder (mm): 1.2, 1.2, 1.5, 1.5

    When the axial bending deformation of the drilling jar exceeds 1.5 °, it should be scrapped.

    When the corrosion depth of the outer cylinder of the drilling jar exceeds 2mm, it should be scrapped.

    The main body and core shaft of the drilling jar cannot be repaired and should be scrapped.


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